1. Technical Field
The present invention relates to a media gateway and a control method thereof and in particular, relates to the media gateway and the control method thereof which autonomously optimize resources of the media gateway.
2. Background Art
Daily progress of communication system is so rapid. In consequence, there are growing demands for communicating by voice, data, a still image and video at high transmission speed in a communication network. In order to cope with the demand, a study on formation of next generation carrier network represented by NGN (Next Generation Network) is being promoted. According to formation of NGN, various existing communication networks such as PSTN (Public Switched Telephone Network) which is a circuit switched network for conventional voice communication and a mobile communication network are unified as an integrated network based on packet communication with an IP (Internet Protocol) technology. A voice signal is transmitted with a VoIP (Voice over Internet Protocol) technology there. Further, a technology to aim at an efficient and seamless connection between different types of networks is also being proposed.
Japanese Patent Publication No. 2004-534439, which is corresponding to International Publication WO2002/087160 and U.S. Publication No. 2004/0166843, and is referred to as a patent document 1 hereinafter, discloses a technology to convey IP traffic between heterogeneous mobile radio systems, for example between a public mobile radio network of 2G/3G (Second generation/third generation) and WLAN (Wireless Local Area Network). According to the technology, each of the heterogeneous mobile radio systems includes an access node (For example, GGSN(Gateway GPRS Support Node), and LMA(Local Mobility Agent)) to a packet data network represented by the Internet. A seamless service between a mobile terminal and the packet data network via the access node is provided. According to the technology, the access node of the second mobile radio network (e.g. WLAN) can only be indirectly connected to the packet data network via the access node of the first mobile radio network (e.g. public mobile radio network of 2G/3G type). The packet data is indirectly transferred, via the access node of the first mobile radio network, from the second mobile radio network to the packet data network connected with the first mobile radio network.
Another technology is disclosed, in which a connection between different types of networks is set up through separately arranging a media gateway as a bearer transmission node and a media gateway controller as a control node. Japanese Patent Publication No. 2005-537700, which is corresponding to International Publication WO2004/006598 and U.S. Publication No. 2006/0153205, and is referred to as a patent document 2, discloses a technology in which a media gateway optimally changes coding using a command transmitted from a media gateway controller. This technology allows for an efficient changeover of codings in terminations at a media gateway based on the command and enables switching between codings that the media gateway is unable to convert into each other. The Media Gateway, after arrival of the command, checks for the connectibility of the terminations of a context with new coding when the media gateway determines, as a result of one or more further commands arriving at the Media Gateway, that it has available current commands to be executed for changing the codings in terminations of the context.
Further, an apparatus is disclosed, in which a connection between different types of networks is set up from resource saving point of view in consideration to an advanced and complicated communication environment. Japanese Patent Publication No. 2006-186982, which is corresponding to U.S. Publication No. 2006/0133353, and is referred to as a patent document 3, discloses a technology with regard to a soft switch device described below. According to this technology, the soft switch device acquires an initial address message IAM at a calling side, and analyzes information of the calling party and the called party based on the acquired initial address message IAM. When it is found that the calling party and the called party are controlled by the same media gateway, the soft switch device informs the media gateways to generate a context and to add TDM (Time Division Multiplexing) semi-permanent physical terminations of time slots, which are corresponding to the calling party and the called party, into the context. Thus, a local loop of TDM voice can be implemented, reduce IP loop of RTP (Real-time Transmission Protocol) streams and efficiently reduce network resources such as steps for digital signal processing, echo cancellation, etc.